Necrotizing enterocolitis induces T lymphocyte-mediated injury in the developing mammalian brain

Hyperbaric oxygen therapy alleviates intestinal and brain damage in experimental necrotizing enterocolitis

Necrotizing enterocolitis is the most common gastrointestinal emergency in newborns. Its etiology involves bacterial colonization, enteral formula feeding, and hypoxic-ischemic injury. The pathology of necrotizing enterocolitis is characterized by coagulation necrosis and bacterial overgrowth, with limited preventative methods available. In addition to affecting the intestine, this disease has long-term neurological consequences for survivors. Hyperbaric oxygen therapy, a well-established treatment for soft tissue infections and injuries caused by hypoperfusion, may serve as an alternative approach for necrotizing enterocolitis. In this study, a necrotizing enterocolitis model was developed in newborn Sprague-Dawley rat pups through the administration of a hyperosmolar formula, combined with exposure to hypothermia and hypoxia. The rat pups received hyperbaric oxygen therapy sessions at 3 absolute atmospheres for 2 hours each, which were administered over 1 or 2 days. The results demonstrated that hyperbaric oxygen therapy significantly reduced mortality in rats with necrotizing enterocolitis and preserved the number of brain cells in the hippocampus. Additionally, hyperbaric oxygen therapy increased the expression of nitric oxide synthase, intestinal fatty acid-binding protein, and superoxide dismutase 3 in the intestine, and elevated superoxide dismutase 3 levels in the hippocampus. These findings suggest that hyperbaric oxygen therapy not only reduces mortality but also mitigates the severity of intestinal and brain lesions in experimental necrotizing enterocolitis, preserving intestinal cell integrity and enhancing antioxidant mechanisms.

Digging deeper into necrotizing enterocolitis: bridging clinical, microbial, and molecular perspectives

Necrotizing Enterocolitis (NEC) is a severe, life-threatening inflammatory condition of the gastrointestinal tract, especially affecting preterm infants. This review consolidates evidence from various biomedical disciplines to elucidate the complex pathogenesis of NEC, integrating insights from clinical, microbial, and molecular perspectives. It emphasizes the modulation of NEC-associated inflammatory pathways by probiotics and novel biologics, highlighting their therapeutic potential. We further critically examine dysbiotic alterations within the gut microbiota, with a particular focus on imbalances in bacterial and viral communities, which may contribute to the onset of NEC. The intricate interactions among toll-like receptor 4 (TLR4), microvascular integrity, immune activation, and the inflammatory milieu are meticulously summarized, offering a sophisticated understanding of NEC pathophysiology. This academic review aims to enhance the etiological comprehension of NEC, promote the development of targeted therapeutic interventions, and impart the significant impact of perinatal factors on the formulation of preventive and curative strategies for the disease.

AQP-4 autoantibodies as potential early diagnostic biomarkers for NEC

BACKGROUND

Necrotizing enterocolitis (NEC) is a severe intestinal disease in neonates. The study aims to identify aquaporin-4 (AQP-4) protein and its autoantibodies as potential biomarkers for early diagnosis of neonatal necrotizing enterocolitis.

METHODS

A prospective cohort study was conducted. Plasma samples from newborns suspected of NEC (n = 75) were collected and divided into the NEC group (n = 30) and the non-NEC group (n = 30) according to the follow-up results for autoimmune microarray analysis. Plasma samples from patients matched for gestational age and weight were selected for an independent validation cohort, including plasma samples from newborns with functional abdominal distension (FAD) (n = 21), preterm infants (PI) (n = 30), and newborns diagnosed with NEC according to Bell criteria (n = 73). Plasma AQP-4 protein and autoantibody (IgG/IgM) levels were detected by ELISA, and the diagnostic performance of AQP-4 protein and autoantibody (IgG/IgM) was evaluated by ROC curve analysis.

RESULTS

Prospective autoantibody microarray analysis revealed a significant increase in AQP-4 autoantibodies in the NEC group. ELISA results confirmed elevated levels of AQP-4 protein and its autoantibodies in the NEC group. The area under the curve (AUC) for AQP-4 autoantibodies in the NEC diagnosis was 0.8999 (NEC I: 0.8571) in the FAD cohort and 0.8537 (NEC I: 0.8032) in the PI cohort. Correspondingly, the AUC for AQP-4 protein was 0.9471 (NEC I: 0.9531) in the FAD cohort and 0.8029 (NEC I: 0.7719) in the PI cohort.

CONCLUSION

Plasma AQP-4 protein and its autoantibodies show high diagnostic value for NEC, offering significant potential for early detection.

Ascending Vaginal Infection in Mice Induces Preterm Birth and Neonatal Morbidity

Preterm birth (PTB; delivery before 37 weeks), the main cause of neonatal death worldwide, can lead to adverse neurodevelopmental outcomes, as well as lung and gut pathology. PTB can be associated with ascending vaginal infection. Ascending Escherichia coli infection in pregnant mice induces PTB and reduces pup survival. The current study demonstrated that this model recapitulates the pathology observed in human preterm neonates (namely, neuroinflammation, lung injury, and gut inflammation). In neonatal brains, there is widespread cell death, microglial activation, astrogliosis, and reduced neuronal density. The utility of this model was validated by assessing the efficacy of maternal cervical gene therapy with an adeno-associated viral vector containing human β defensin 3. This improved pup survival and reduced tumor necrosis factor alpha mRNA expression in perinatal pup brains exposed to E. coli. This model provides a unique opportunity to evaluate the therapeutic benefit of preterm labor interventions on perinatal pathology.

Gut-Brain Axis in Preterm Infants with Surgical Necrotizing Enterocolitis

Necrotizing enterocolitis (NEC) affects 5 to 10% of very low-birth-weight infants and remains a leading cause of mortality and long-term morbidity. Preterm infants with NEC, especially those requiring surgery, have higher inflammatory markers in the blood, severe white matter abnormalities on brain imaging, and adverse neurodevelopmental outcomes. This review presents current evidence regarding the clinical factors associated with brain injury in preterm infants with NEC needing surgical intervention. Studies that evaluate neuroprotective strategies to prevent brain injury are greatly needed to improve neurodevelopmental outcomes in high-risk preterm infants with NEC. · NEC is associated with white matter, grey matter, and cerebellar injury in neonates.. · Clinical and histopathological factors are associated with gut-associated brain injury in NEC.. · Neuroprotective strategies and intervention are greatly needed in infants with surgical NEC..

Glycyrrhizin alleviates brain injury in necrotizing enterocolitis model mice by suppressing HMGB1/TLR4 pathway

BACKGROUND

Systemic inflammation from necrotizing enterocolitis (NEC) can adversely affect the developing central nervous system. Evidence indicates that gut-derived high mobility group box 1 (HMGB1) can migrate to the brain and activate microglia.

OBJECTIVE

To determine if glycyrrhizin, an HMGB1 inhibitor, can reduce microglial pyroptosis and neuroinflammatory injury in NEC by modulating the HMGB1/ Toll-like receptor 4 (TLR4) pathway.

METHODS

HMGB1 levels were analyzed in clinical NEC samples. NEC models were induced through hypoxia, cold exposure, and overfeeding. BV2 microglial cells were stimulated with lipopolysaccharide (LPS) to mimic NEC-induced inflammation. Histological assessments were performed on the intestines and brain. Cell proliferation was evaluated employing the cell counting kit-8 (CCK-8) assay. Real-time quantitative polymerase chain reaction (RT-qPCR) quantified mRNA levels of HMGB1, TLR4, nuclear factor kappa B p65 (NF-κB p65), tumor necrosis factor-alpha (TNF-α), interleukin (IL)-1β, IL-6, and IL-18. Protein expression was analyzed using western blotting, ELISA, immunohistochemistry, and immunofluorescence for key markers. Small interfering RNAs (siRNAs) targeted HMGB1 and TLR4.

RESULTS

Elevated levels of HMGB1 were observed in both clinical NEC samples and the NEC mouse model, with higher concentrations detected in feces, cerebrospinal fluid, and brain tissue. In the NEC patients, Spearman analysis revealed a significant correlation between elevated HMGB1 levels in CSF and fecal supernatant. Treatment with glycyrrhizin appeared to mitigate brain damage in the NEC mice and seemed to reduce LPS-induced inflammation in BV2 microglial cells. Additionally, glycyrrhizin enhanced the expression of tight junction protein occludin and myelin basic protein (MBP), which may be associated with improvements in behavioral performance observed in the NEC mice. Furthermore, glycyrrhizin treatment resulted in a reduction of key inflammatory mediators, including NF-κB p65, NOD-like receptor protein 3 (NLRP3), Caspase-1 p20, gasdermin D (GSDMD), IL-1β, and IL-18 in brain tissue and BV2 microglial cells. These results suggest that glycyrrhizin may exert its effects, at least in part, through modulation of the HMGB1/TLR4 signaling pathway.

CONCLUSION

Glycyrrhizin effectively mitigates neuroinflammatory injury in NEC by inhibiting the HMGB1/TLR4 pathway, preserving MBP, protecting the blood-brain barrier, and reducing pyroptosis in BV2 microglial cells. These findings suggest that glycyrrhizin may provide a novel therapeutic approach for improving neurological outcomes in NEC.

Epigenetic Insights Into Necrotizing Enterocolitis: Unraveling Methylation-Regulated Biomarkers

Necrotizing enterocolitis (NEC) is a multifactorial gastrointestinal disease with high morbidity and mortality among premature infants. This study aimed to identify novel methylation-regulated biomarkers in NEC intestinal tissue through multiomics analysis. We analyzed DNA methylation and transcriptome datasets from ileum and colon tissues of patients with NEC. We identify methylation-related differential genes (MrDEGs) based on the rule that the degree of methylation in the promoter region is inversely proportional to RNA transcription. These MrDEGs included ADAP1, GUCA2A, BCL2L14, FUT3, MISP, USH1C, ITGA3, UNC93A and IL22RA1. Single-cell data revealed that MrDEGs were mainly located in the intestinal epithelial part of intestinal tissue. These MrDEGs were verified through Target gene bisulfite sequencing and RT-qPCR. We successfully identified and verified the ADAP1, GUCA2A, IL22RA1 and MISP, primarily expressed in intestinal epithelial villus cells through single-cell data. Through single-gene gene set enrichment analysis, we found that these genes participate mainly in the pathological process of T-cell differentiation and the suppression of intestinal inflammation in NEC. This study enhances our understanding of the pathogenesis of NEC and may promote the development of new precision medicine methods for NEC prediction and diagnosis.

Evaluation of Faecal Microbiota Following Probiotics in Infants of Mothers with Gestational Diabetes Mellitus Trial: Protocol for Double-Blind Placebo-Controlled Randomized Trial

(1) Background: The incidence of gestational diabetes mellitus (GDM) is rising globally. The current evidence indicates that GDM, especially in conjunction with maternal overweight, can alter the composition of infants' gut microbiota, potentially increasing the risk of inflammatory diseases, metabolic disorders, and neurodevelopmental issues later in life. Probiotic supplantation early in life might establish eubiosis and mitigate future complications. To best of our knowledge, no study has evaluated the effects of probiotics on gut dysbiosis in the infants of mothers with GDM. (2) Methods: This study will be a single-centre, double-blind, randomized, placebo-controlled trial enrolling sixty neonates born after 35 weeks of gestation to mothers with GDM. The participants will be randomly assigned to receive either a triple-strain probiotic or a placebo for four months. The primary objective is to assess the effectiveness of probiotic supplementation in correcting gut dysbiosis in the infants of mothers with GDM at four months of age. Faecal microbiome composition shall be estimated using 16SrRNA and shotgun sequencing. The secondary outcomes will include the quantification of faecal short-chain fatty acids at birth and at four months, as well as growth and developmental assessments at four, twelve, and twenty-four months. (3) Trial registration: This trial protocol is registered (ACTRN12624000930583p) in the Australian Clinical Trials registry (ANZCTR).

Approaches for studying neuroimmune interactions in Alzheimer's disease

Peripheral immune cells play an important role in the pathology of Alzheimer's disease (AD), impacting processes such as amyloid and tau protein aggregation, glial activation, neuronal integrity, and cognitive decline. Here, we examine cutting-edge strategies - encompassing animal and cellular models - used to investigate the roles of peripheral immune cells in AD. Approaches such as antibody-mediated depletion, genetic ablation, and bone marrow chimeras in mouse models have been instrumental in uncovering T, B, and innate immune cell disease-modifying functions. However, challenges such as specificity, off-target effects, and differences between human and mouse immune systems underscore the need for more human-relevant models. Emerging multicellular models replicating critical aspects of human brain tissue and neuroimmune interactions increasingly offer fresh insights into the role of immune cells in AD pathogenesis. Refining these methodologies can deepen our understanding of immune cell contributions to AD and support the development of novel immune-related therapeutic interventions.

Comparing Healthcare Needs in Extremely Low Birth Weight Infants With NEC and Spontaneous Intestinal Perforation

BACKGROUND

Necrotizing enterocolitis (NEC) and spontaneous intestinal perforation (SIP) affect 6-8% of extremely low birth weight (ELBW) infants. SIP has lower mortality than NEC, but with similar short-term morbidity in length of stay, growth failure, and supplemental oxygen requirements. Comparative long-term neurodevelopmental outcomes have not been clarified.

METHODS

Data were prospectively collected from 59 North American neonatal units, regarding ELBW infants (401-1000 g or 22-27 weeks gestational age) born between 2011 and 2018 and evaluated again at 16-26 months corrected age. Outcomes were collected from infants with laparotomy-confirmed NEC, laparotomy-confirmed SIP, and those without NEC or SIP. The primary outcome was severe neurodevelopmental disability. Secondary outcomes were weight <10th percentile, medical readmission, post-discharge surgery and medical support at home. Adjusted risk ratios (ARR) were calculated.

RESULTS

Of 13,673 ELBW infants, 6391 (47%) were followed including 93 of 232 (40%) with NEC and 100 of 235 (42%) with SIP. There were no statistically significant differences in adjusted risk of any outcomes when directly comparing NEC to SIP (ARR 2.35; 95% CI 0.89, 6.26). However, infants with NEC had greater risk of severe neurodevelopmental disability (ARR 1.43; 1.09-1.86), rehospitalization (ARR 1.46; 1.17-1.82), and post-discharge surgery (ARR 1.82; 1.48-2.23) compared to infants without NEC or SIP. Infants with SIP only had greater risk of post-discharge surgery (ARR 1.64; 1.34-2.00) compared to infants without NEC or SIP.

CONCLUSIONS

ELBW infants with NEC had significantly increased risk of severe neurodevelopmental disability and post-discharge healthcare needs, consistent with prior literature. We now know infants with SIP also have increased healthcare needs.

LEVELS OF EVIDENCE

Level II.

Ccr2-dependent monocytes exacerbate intestinal inflammation and modulate gut serotonergic signaling following traumatic brain injury

BACKGROUND

Traumatic brain injury (TBI) leads to acute gastrointestinal dysfunction and mucosal damage, resulting in feeding intolerance. C-C motif chemokine receptor 2 (Ccr2 + ) monocytes are crucial immune cells that regulate the gut's inflammatory response via the brain-gut axis. Using Ccr2 ko mice, we investigated the intricate interplay between these cells to better elucidate the role of systemic inflammation after TBI.

METHODS

A murine-controlled cortical impact model was used, and results were analyzed on postinjury days 1 and 3. The experimental groups included (1) sham C57Bl/6 wild type (WT), (2) TBI WT, (3) sham Ccr2 ko , and (4) TBI Ccr2 ko . Mice were euthanized on postinjury days 1 and 3 to harvest the ileum and study intestinal dysfunction and serotonergic signaling using a combination of quantitative real-time polymerase chain reaction, immunohistochemistry, fluorescein isothiocyanate-dextran motility assays, and flow cytometry. Student's t test and one-way analysis of variance were used for statistical analysis, with significance achieved when p < 0.05.

RESULTS

Traumatic brain injury resulted in severe dysfunction and dysmotility of the small intestine in WT mice as established by significant upregulation of inflammatory cytokines iNOS , Lcn2 , TNFα , and IL1β and the innate immunity receptor toll-like receptor 4 ( Tlr4 ). This was accompanied by disruption of genes related to serotonin synthesis and degradation. Notably, Ccr2 ko mice subjected to TBI showed substantial improvements in intestinal pathology. Traumatic brain injury Ccr2 ko groups demonstrated reduced expression of inflammatory mediators ( iNOS , Lcn2 , IL1β , and Tlr4 ) and improvement in serotonin synthesis genes, including tryptophan hydroxylase 1 ( Tph1 ) and dopa decarboxylase ( Ddc ).

CONCLUSION

Our study reveals a critical role for Ccr2 + monocytes in modulating intestinal homeostasis after TBI. Ccr2 + monocytes aggravate intestinal inflammation and alter gut-derived serotonergic signaling. Therefore, targeting Ccr2 + monocyte-dependent responses could provide a better understanding of TBI-induced gut inflammation. Further studies are required to elucidate the impact of these changes on brain neuroinflammation and cognitive outcomes.

Global Literature Analysis of Organoid and Organ-on-Chip Research

Organoids and cells in organ-on-chip platforms replicate higher-level anatomical, physiological, or pathological states of tissues and organs. These technologies are widely regarded by academia, the pharmacological industry and regulators as key biomedical developments. To map advances in this emerging field, a literature analysis of 16,000 article metadata based on a quality-controlled text-mining algorithm is performed. The analysis covers titles, keywords, and abstracts of categorized academic publications in the literature and preprint databases published after 2010. The algorithm identifies and tracks 149 and 107 organs or organ substructures modeled as organoids and organ-on-chip, respectively, stem cell sources, as well as 130 diseases, and 16 groups of organisms other than human and mouse in which organoid/organ-on-chip technology is applied. The analysis illustrates changing diversity and focus in organoid/organ-on-chip research and captures its geographical distribution. The downloadable dataset provided is a robust framework for researchers to interrogate with their own questions.

Neurodevelopmental outcomes of preterm with necrotizing enterocolitis: a systematic review and meta-analysis

While neonatal necrotising enterocolitis (NEC) is associated with high mortality rates in newborns, survivors can face long-term sequelae. However, the relationship between NEC and neurodevelopmental impairment (NDI) in preterm infants remains unclear. To explore the relationship between neonatal NEC and neurodevelopmental outcomes in preterm infants, we searched PubMed, EMBASE, and the Cochrane Library from their inception to February 2024 for relevant studies. Studies included were cohort or case-control studies reporting neurodevelopmental outcomes of NEC in preterm infants. Two independent investigators extracted data regarding brain damage and neurodevelopmental outcomes in these infants at a corrected age exceeding 12 months. Odds ratios (ORs) were pooled using a random effects model. We included 15 cohort studies and 18 case-control studies, encompassing 60,346 infants. Meta-analysis of unadjusted and adjusted ORs demonstrated a significant association between NEC and increased odds of NDI (OR 2.15, 95% CI 1.9-2.44; aOR 1.89, 95% CI 1.46-2.46). Regarding brain injury, pooled crude ORs indicated an association of NEC with severe intraventricular haemorrhage (IVH) (OR 1.42, 95% CI 1.06-1.92) and periventricular leucomalacia (PVL) (OR 2.55, 95% CI 1.76-3.69). When compared with conservatively treated NEC, surgical NEC potentially carries a higher risk of NDI (OR 1.78, 95% CI 1.09-2.93) and severe IVH (OR 1.57, 95% CI 1.20-2.06). However, the risk of PVL did not show a significant difference (OR 1.60, 95% CI 0.47-5.40).

CONCLUSIONS

 Our meta-analysis provides evidence suggesting an association between NEC and NDI. Additionally, the severity of intestinal lesions appears to correlate with a higher risk of NDI. Further high-quality studies with comprehensive adjustments for potential confounding factors are required to definitively establish whether the association with NDI is causal.

WHAT IS KNOWN

• NEC is a serious intestinal disease in the neonatal period with a high mortality rate, and surviving children may have digestive system sequelae. • Compared with non-NEC preterm infants, the reported incidences of brain injury and neurodevelopmental disorders in NEC preterm infants are not the same.

WHAT IS NEW

• The risk of neonatal brain injury and neurodevelopmental disorders in preterm infants with NEC is higher than that in non-NEC infants, and the risk of NDI in surgical NEC infants is higher than that in the conservative treatment group. • NEC may increase the risk of motor, cognitive, language development delays, and attention deficits in children.

Development of an artificial intelligence-based multimodal model for assisting in the diagnosis of necrotizing enterocolitis in newborns: a retrospective study

Objective

The purpose of this study is to develop a multimodal model based on artificial intelligence to assist clinical doctors in the early diagnosis of necrotizing enterocolitis in newborns.

Methods

This study is a retrospective study that collected the initial laboratory test results and abdominal x-ray image data of newborns (non-NEC, NEC) admitted to our hospital from January 2022 to January 2024.A multimodal model was developed to differentiate multimodal data, trained on the training dataset, and evaluated on the validation dataset. The interpretability was enhanced by incorporating the Gradient-weighted Class Activation Mapping (GradCAM) analysis to analyze the attention mechanism of the multimodal model, and finally compared and evaluated with clinical doctors on external datasets.

Results

The dataset constructed in this study included 11,016 laboratory examination data from 408 children and 408 image data. When applied to the validation dataset, the area under the curve was 0.91, and the accuracy was 0.94. The GradCAM analysis shows that the model's attention is focused on the fixed dilatation of the intestinal folds, intestinal wall edema, interintestinal gas, and portal venous gas. External validation demonstrated that the multimodal model had comparable accuracy to pediatric doctors with ten years of clinical experience in identification.

Conclusion

The multimodal model we developed can assist doctors in early and accurate diagnosis of NEC, providing a new approach for assisting diagnosis in underdeveloped medical areas.

Microbiome and its impact on fetal and neonatal brain development: current opinion in pediatrics

PURPOSE OF REVIEW

Emerging evidence suggests that the gut microbiota and its metabolites regulate neurodevelopment and cognitive functioning via a bi-directional communication system known as the microbiota-gut-brain axis (MGBA).

RECENT FINDINGS

The MGBA influences brain development and function via the hypothalamic-pituitary axis, the vagal nerve, immune signaling, bacterial production of neurotransmitters, and microbial metabolites like short-chain fatty acids, tryptophan derivatives, and bile acids. Animal studies show fetal neurodevelopment is mediated by maternal microbiota derivatives, immune activation, and diet. Furthermore, manipulation of the microbiota during critical windows of development, like antibiotic exposure and fecal microbiota transplantation, can affect cognitive functioning and behavior in mice. Evidence from human studies, particularly in preterm infants, also suggests that a disrupted gut microbiota colonization may negatively affect neurodevelopment. Early microbial signatures were linked to favorable and adverse neurodevelopmental outcomes.

SUMMARY

The link between the gut microbiota and the brain is evident. Future studies, including experimental studies, larger participant cohort studies with longitudinal analyses of microbes, their metabolites, and neurotransmitters, and randomized controlled trials are warranted to further elucidate the mechanisms of the MGBA. Identification of early, predictive microbial markers could pave the way for the development of novel early microbiota-based intervention strategies, such as targeted probiotics, and vaginal or fecal microbiota transplantation, aimed at improving infant neurodevelopment.

Subventricular zone stem cell niche injury is associated with intestinal perforation in preterm infants and predicts future motor impairment

Brain injury is highly associated with preterm birth. Complications of prematurity, including spontaneous or necrotizing enterocolitis (NEC)-associated intestinal perforations, are linked to lifelong neurologic impairment, yet the mechanisms are poorly understood. Early diagnosis of preterm brain injuries remains a significant challenge. Here, we identified subventricular zone echogenicity (SVE) on cranial ultrasound in preterm infants following intestinal perforations. The development of SVE was significantly associated with motor impairment at 2 years. SVE was replicated in a neonatal mouse model of intestinal perforation. Examination of the murine echogenic subventricular zone (SVZ) revealed NLRP3-inflammasome assembly in multiciliated FoxJ1+ ependymal cells and a loss of the ependymal border in this postnatal stem cell niche. These data suggest a mechanism of preterm brain injury localized to the SVZ that has not been adequately considered. Ultrasound detection of SVE may serve as an early biomarker for neurodevelopmental impairment after inflammatory disease in preterm infants.

Necrotizing enterocolitis: current understanding of the prevention and management

Necrotizing enterocolitis (NEC) is one of the diseases in neonates, with a high morbidity and mortality rate, especially in preterm infants. This review aimed to briefly introduce the latest epidemiology, susceptibility factors, and clinical diagnosis and presentation of NEC. We also organized new prevention strategies by risk factors according to different pathogeneses and then discussed new treatment methods based on Bell's staging and complications, and the classification of mild to high severity based on clinical and imaging manifestations. Such a generalization will help clinicians and researchers to gain a deeper understanding of the disease and to conduct more targeted classification, grading prevention, and exploration. We focused on prevention and treatment of the early and suspected stages of NEC, including the discovery of novel biomarkers and drugs to control disease progression. At the same time, we discussed its clinical application, future development, and shortcomings.

Butyrate suppresses experimental necrotizing enterocolitis-induced brain injury in mice

Background

Necrotizing enterocolitis (NEC) is a devastating disease in premature infants, and 50% of infants with surgical NEC develop neurodevelopmental defects. The mechanisms by which NEC-induced cytokine release and activation of inflammatory cells in the brain mediate neuronal injury, and whether enteral immunotherapy attenuates NEC-associated brain injury remain understudied. Based on our prior work, which demonstrated that experimental NEC-like intestinal injury is attenuated by the short-chain fatty acid, butyrate, in this study, we hypothesize that NEC-induced brain injury would be suppressed by enteral butyrate supplementation.

Methods

A standardized NEC mouse model [enteral formula feeding, lipopolysaccharide (LPS), and hypoxia] was used. Mice were randomized into the following groups: control, NEC, butyrate pretreated NEC, and butyrate control. NEC scoring (1-4 with 4 representing severe injury) was performed on ileal sections using a validated scoring system. Intestinal and brain lysates were used to assess inflammation, proinflammatory signaling, and apoptosis.

Results

NEC-induced intestinal injury was attenuated by butyrate supplementation. NEC-induced microglial activation in the cerebral cortex and hippocampus was suppressed with butyrate. NEC increased the number of activated microglial cells but decreased the number of oligodendrocytes. Butyrate pretreatment attenuated these changes. Increased activation of proinflammatory Toll-like receptor signaling, cytokine expression, and induction of GFAP and IBA1 in the cerebral cortex observed with NEC was suppressed with butyrate.

Conclusion

Experimental NEC induced inflammation and activation of microglia in several regions of the brain, most prominently in the cortex. NEC-induced neuroinflammation was suppressed with butyrate pretreatment. The addition of short-chain fatty acids to diet may be used to attenuate NEC-induced intestinal injury and neuroinflammation in preterm infants.

Cholinergic Anti-inflammatory Pathway Attenuates Acute Liver Failure Through Inhibiting MAdCAM1/α4β7-mediated Gut-derived Proinflammatory Lymphocytes Accumulation

BACKGROUND & AIMS

The function of cholinergic anti-inflammatory pathway (CAP) in acute liver failure (ALF) with inflammatory storm remains indefinite. The liver-gut axis has been proved to be crucial for liver homeostasis. Investigation about CAP regulation on liver-gut axis would enrich our understanding over cholinergic anti-inflammatory mechanism.

METHODS

Co-injection of lipopolysaccharide and D-galactosamine was used to establish the model of ALF. PNU-282987 was used to activate the CAP. Histological staining, real-time polymerase chain reaction, Western blotting, RNA sequencing, and flow cytometry were conducted. Liver biopsy specimens and patients' serum from patients with liver failure were also analyzed.

RESULTS

We confirmed that activating the CAP alleviated hepatocyte destruction, accompanied by a significant decrease in hepatocyte apoptosis, pro-inflammatory cytokines, and NLRP3 inflammasome activation. Moreover, hepatic MAdCAM1 and serum MAdCAM1 levels were induced in ALF, and MAdCAM1 levels were positively correlated with the extent of liver damage and the expression of pro-inflammatory markers. Furthermore, activating the CAP mainly downregulated ectopic expression of MAdCAM1 on endothelial cells, and inhibition of NF-κB p65 nuclear translocation was partly attributed to the decreased MAdCAM1. Notably, in ALF, the aberrant hepatic expression of MAdCAM1 subsequently recruited gut-derived α4β7+ CD4+T cells to the liver, which exhibited an augmented IFN-γ-secreting and IL-17-producing phenotype. Finally, we revealed that the levels of serum and hepatic MAdCAM1 were elevated in patients with liver failure and closely correlated with clinical course. Increasing hepatic infiltration of β7+ cells were also confirmed in patients.

CONCLUSIONS

Activating the CAP attenuated liver injury by inhibiting MAdCAM1/α4β7 -mediated gut-derived proinflammatory lymphocytes infiltration, which provides a potential therapeutic target for ALF.

Evaluation of white matter microstructural alterations in premature infants with necrotizing enterocolitis

Background

Preterm infants with necrotizing enterocolitis (NEC) are at high risk of adverse neurodevelopmental outcomes. The aim of this study was to explore the value of diffusion tensor imaging (DTI) combined with serum C-reactive protein (CRP) and procalcitonin (PCT) in evaluating alterations of white matter (WM) microstructure in preterm infants with NEC.

Methods

A retrospective cross-sectional study was conducted in which all participants were consecutively enrolled at The Third Affiliated Hospital of Zhengzhou University from June 2017 and October 2021. Data from 30 preterm infants with NEC [mean gestational age at birth 31.41±1.15 weeks; mean age at magnetic resonance imaging (MRI) 37.53±3.08 weeks] and 40 healthy preterm infants with no NEC were recorded (mean gestational age at birth 32.27±2.09 weeks; mean age at MRI 37.15±3.23 weeks). WM was used to obtain the fractional anisotropy (FA) and mean diffusivity (MD) values of the regions of interest (ROIs). Additionally, serum levels of CRP and PCT were determined. Spearman correlation analysis was performed between the WM-derived parameters, CRP level, and the PCT serum index.

Results

Preterm infants with NEC had reduced FA values and elevated MD values in WM regions [posterior limbs of the internal capsule (PLIC), lentiform nucleus (LN), frontal white matter (FWM)] compared to the control group (P<0.05). Additionally, the FA of the PLIC was negatively correlated with serum CRP (r=-0.846; P<0.05) and PCT (r=-0.843; P<0.05). Meanwhile, the MD of PLIC was positively correlated with serum CRP (r=0.743; P<0.05) and PCT (r=0.743; P<0.05, respectively). The area under the curve (AUC) of FA and MD combined with CRP and PCT in the diagnosis of WM microstructure alterations with NEC was 0.968, representing a considerable improvement in predicted efficacy over single indicators, including FA [AUC: 0.938; 95% confidence interval (CI): 0.840-0.950], MD (AUC: 0.807; 95% CI: 0.722-0.838), CRP (AUC: 0.867; 95% CI: 0.822-0.889), and PCT (AUC: 0.706; 95% CI: 0.701-0.758).

Conclusions

WM can noninvasively and quantitatively assess the WM microstructure alterations in preterm infants with NEC. WM combined with serum CRP and PCT demonstrated superior performance in detecting and evaluating WM microstructure alterations in preterm infants with NEC.

Role of the gut-microbiota-metabolite-brain axis in the pathogenesis of preterm brain injury

Brain injury, a common complication in preterm infants, includes the destruction of the key structural and functional connections of the brain and causes neurodevelopmental disorders; it has high morbidity and mortality rates. The exact mechanism underlying brain injury in preterm infants is unclear. Intestinal flora plays a vital role in brain development and the maturation of the immune system in infants; however, detailed understanding of the gut microbiota-metabolite-brain axis in preterm infants is lacking. In this review, we summarise the key mechanisms by which the intestinal microbiota contribute to neurodevelopment and brain injury in preterm infants, with special emphasis on the influence of microorganisms and their metabolites on the regulation of neurocognitive development and neurodevelopmental risks related to preterm birth, infection and neonatal necrotising enterocolitis (NEC). This review provides support for the development and application of novel therapeutic strategies, including probiotics, prebiotics, synbiotics, and faecal bacteria transplantation targeting at brain injury in preterm infants.

Early-life gut microbiota and neurodevelopment in preterm infants: a narrative review

Infants born preterm are at a high risk of both gut microbiota (GM) dysbiosis and neurodevelopmental impairment. While the link between early dysbiosis and short-term clinical outcomes is well established, the relationship with long-term infant health has only recently gained interest. Notably, there is a significant overlap in the developmental windows of GM and the nervous system in early life. The connection between GM and neurodevelopment was first described in animal models, but over the last decade a growing body of research has also identified GM features as one of the potential mediators for human neurodevelopmental and neuropsychiatric disorders. In this narrative review, we provide an overview of the developing GM in early life and its prospective relationship with neurodevelopment, with a focus on preterm infants. Animal models have provided evidence for emerging pathways linking early-life GM with brain development. Furthermore, a relationship between both dynamic patterns and static features of the GM during preterm infants' early life and brain maturation, as well as neurodevelopmental outcomes in early childhood, was documented. Future human studies in larger cohorts, integrated with studies on animal models, may provide additional evidence and help to identify predictive biomarkers and potential therapeutic targets for healthy neurodevelopment in preterm infants.

Host insulin resistance caused by Porphyromonas gingivalis-review of recent progresses

Porphyromonas gingivalis (P. gingivalis) is a Gram-negative oral anaerobic bacterium that plays a key role in the pathogenesis of periodontitis. P. gingivalis expresses a variety of virulence factors that disrupt innate and adaptive immunity, allowing P. gingivalis to survive and multiply in the host and destroy periodontal tissue. In addition to periodontal disease, P.gingivalis is also associated with systemic diseases, of which insulin resistance is an important pathological basis. P. gingivalis causes a systemic inflammatory response, disrupts insulin signaling pathways, induces pancreatic β-cell hypofunction and reduced numbers, and causes decreased insulin sensitivity leading to insulin resistance (IR). In this paper, we systematically review the studies on the mechanism of insulin resistance induced by P. gingivalis, discuss the association between P. gingivalis and systemic diseases based on insulin resistance, and finally propose relevant therapeutic approaches. Overall, through a systematic review of the mechanisms related to systemic diseases caused by P. gingivalis through insulin resistance, we hope to provide new insights for future basic research and clinical interventions for related systemic diseases.

Human milk oligosaccharides reduce necrotizing enterocolitis-induced neuroinflammation and cognitive impairment in mice

Necrotizing enterocolitis (NEC) is the leading cause of morbidity and mortality in premature infants. One of the most devastating complications of NEC is the development of NEC-induced brain injury, which manifests as impaired cognition that persists beyond infancy and which represents a proinflammatory activation of the gut-brain axis. Given that oral administration of the human milk oligosaccharides (HMOs) 2'-fucosyllactose (2'-FL) and 6'-sialyslactose (6'-SL) significantly reduced intestinal inflammation in mice, we hypothesized that oral administration of these HMOs would reduce NEC-induced brain injury and sought to determine the mechanisms involved. We now show that the administration of either 2'-FL or 6'-SL significantly attenuated NEC-induced brain injury, reversed myelin loss in the corpus callosum and midbrain of newborn mice, and prevented the impaired cognition observed in mice with NEC-induced brain injury. In seeking to define the mechanisms involved, 2'-FL or 6'-SL administration resulted in a restoration of the blood-brain barrier in newborn mice and also had a direct anti-inflammatory effect on the brain as revealed through the study of brain organoids. Metabolites of 2'-FL were detected in the infant mouse brain by nuclear magnetic resonance (NMR), whereas intact 2'-FL was not. Strikingly, the beneficial effects of 2'-FL or 6'-SL against NEC-induced brain injury required the release of the neurotrophic factor brain-derived neurotrophic factor (BDNF), as mice lacking BDNF were not protected by these HMOs from the development of NEC-induced brain injury. Taken in aggregate, these findings reveal that the HMOs 2'-FL and 6'-SL interrupt the gut-brain inflammatory axis and reduce the risk of NEC-induced brain injury.NEW & NOTEWORTHY This study reveals that the administration of human milk oligosaccharides, which are present in human breast milk, can interfere with the proinflammatory gut-brain axis and prevent neuroinflammation in the setting of necrotizing enterocolitis, a major intestinal disorder seen in premature infants.

Human brain microphysiological systems in the study of neuroinfectious disorders

Microphysiological systems (MPS) are 2D or 3D multicellular constructs able to mimic tissue microenvironments. The latest models encompass a range of techniques, including co-culturing of various cell types, utilization of scaffolds and extracellular matrix materials, perfusion systems, 3D culture methods, 3D bioprinting, organ-on-a-chip technology, and examination of tissue structures. Several human brain 3D cultures or brain MPS (BMPS) have emerged in the last decade. These organoids or spheroids are 3D culture systems derived from induced pluripotent cells or embryonic stem cells that contain neuronal and glial populations and recapitulate structural and physiological aspects of the human brain. BMPS have been introduced recently in the study and modeling of neuroinfectious diseases and have proven to be useful in establishing neurotropism of viral infections, cell-pathogen interactions needed for infection, assessing cytopathological effects, genomic and proteomic profiles, and screening therapeutic compounds. Here we review the different methodologies of organoids used in neuroinfectious diseases including spheroids, guided and unguided protocols as well as microglia and blood-brain barrier containing models, their specific applications, and limitations. The review provides an overview of the models existing for specific infections including Zika, Dengue, JC virus, Japanese encephalitis, measles, herpes, SARS-CoV2, and influenza viruses among others, and provide useful concepts in the modeling of disease and antiviral agent screening.

New insights into the pathogenesis of necrotizing enterocolitis and the dawn of potential therapeutics

Necrotizing enterocolitis (NEC) is a devastating gastrointestinal disorder in premature infants that causes significant morbidity and mortality. Research efforts into the pathogenesis of NEC have discovered a pivotal role for the gram-negative bacterial receptor, Toll-like receptor 4 (TLR4), in its development. TLR4 is activated by dysbiotic microbes within the intestinal lumen, which leads to an exaggerated inflammatory response within the developing intestine, resulting in mucosal injury. More recently, studies have identified that the impaired intestinal motility that occurs early in NEC has a causative role in disease development, as strategies to enhance intestinal motility can reverse NEC in preclinical models. There has also been broad appreciation that NEC also contributes to significant neuroinflammation, which we have linked to the effects of gut-derived pro-inflammatory molecules and immune cells which activate microglia in the developing brain, resulting in white matter injury. These findings suggest that the management of the intestinal inflammation may secondarily be neuroprotective. Importantly, despite the significant burden of NEC on premature infants, these and other studies have provided a strong rationale for the development of small molecules with the capability of reducing NEC severity in pre-clinical models, thus guiding the development of specific anti-NEC therapies. This review summarizes the roles of TLR4 signaling in the premature gut in the pathogenesis of NEC, and provides insights into optimal clinical management strategies based upon findings from laboratory studies.

What animal model should I use to study necrotizing enterocolitis?

Unfortunately, we are all too familiar with the statement: "Necrotizing enterocolitis remains the leading cause of gastrointestinal surgical emergency in preterm neonates". It's been five decades since the first animal models of necrotizing enterocolitis (NEC) were described. There remains much investigative work to be done on identifying various aspects of NEC, ranging from the underlying mechanisms to treatment modalities. Experimental NEC is mainly focused on a rat, mouse, and piglet models. Our aim is to not only highlight the pros and cons of these three main models, but to also present some of the less-used animal models that have contributed to the body of knowledge about NEC. Choosing an appropriate model is essential to conducting effective research and answering the questions asked. As such, this paper reviews some of the variations that come with each model.

Gut Microbiome-Brain Axis as an Explanation for the Risk of Poor Neurodevelopment Outcome in Preterm Infants with Necrotizing Enterocolitis

Necrotizing Enterocolitis (NEC) is characterized by an inflammation of intestinal tissue that primarily affects premature infants. It is the most common and devastating gastrointestinal morbidity of prematurity, but beyond intestinal morbidity, this condition has also been associated with an increased risk of neurodevelopmental delays that persist beyond infancy. Prematurity, enteral feeding, bacterial colonization, and prolonged exposure to antibiotics are all risk factors that predispose preterm infants to NEC. Interestingly, these factors are all also associated with the gut microbiome. However, whether or not there is a connection between the microbiome and the risk of neurodevelopmental delays in infants after NEC is still an emerging area of research. Furthermore, how microbes in the gut could impact a distant organ such as the brain is also poorly understood. In this review, we discuss the current understanding of NEC and the role of the gut microbiome-brain axis in neurodevelopmental outcomes after NEC. Understanding the potential role of the microbiome in neurodevelopmental outcomes is important as the microbiome is modifiable and thus offers the hope of improved therapeutic options. We highlight the progress and limitations in this field. Insights into the gut microbiome-brain axis may offer potential therapeutic approaches to improve the long-term outcomes of premature infants.

Neurodevelopmental outcome of infants who develop necrotizing enterocolitis: The gut-brain axis

Necrotizing enterocolitis (NEC) poses a significant risk for neurodevelopmental impairment in extremely preterm infants. The gut microbiota shapes the development of the gut, immune system, and the brain; and dysbiosis drive neonatal morbidities including NEC. In this chapter, we delineate a gut-brain axis linking gut microbiota to the adverse neurological outcomes in NEC patients. We propose that in NEC, immaturity of the microbiome along with aberrant gut microbiota-driven immaturity of the gut barrier and immune system can lead to effects including systemic inflammation and circulating microbial mediators. This nexus of gut microbiota-driven systemic effects further interacts with a likewise underdeveloped blood-brain barrier to regulate neuroinflammation and neurodevelopment. Targeting deviant gut-brain axis signaling presents an opportunity to improve the neurodevelopmental outcomes of NEC patients.

Role of gut-brain axis in neurodevelopmental impairment of necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is a common gastrointestinal disease of preterm infants with high morbidity and mortality. In survivors of NEC, one of the leading causes of long-term morbidity is the development of severe neurocognitive injury. The exact pathogenesis of neurodevelopmental delay in NEC remains unknown, but microbiota is considered to have dramatic effects on the development and function of the host brain via the gut-brain axis. In this review, we discuss the characteristics of microbiota of NEC, the impaired neurological outcomes, and the role of the complex interplay between the intestinal microbiota and brain to influence neurodevelopment in NEC. The increasing knowledge of microbial-host interactions has the potential to generate novel therapies for manipulating brain development in the future.

Review of Necrotizing Enterocolitis and Spontaneous Intestinal Perforation Clinical Presentation, Treatment, and Outcomes

The Necrotizing Enterocolitis Surgery Trial (NEST) highlights the importance of distinguishing necrotizing enterocolitis (NEC) from spontaneous intestinal perforation (SIP) when developing surgical treatment plans. Further research is needed to increase the accuracy of this distinction, but even with our current abilities to do this initial laparotomy appears to be optimal for infants with presumed NEC. The preferred initial operation for those with SIP is more equivocal. Rates of NEC are likely decreasing slowly, whereas those with SIP are not. New imaging modalities, especially ultrasound, are becoming more useful but require more detailed investigation. Understanding the mechanisms causing these two conditions remains of paramount importance.

Clinical impact of NEC-associated sepsis on outcomes in preterm infants

OBJECTIVE

To determine risk factors and outcomes of necrotizing enterocolitis (NEC)-associated sepsis in infants with NEC.

METHODS

A retrospective review comparing demographic and clinical information in infants with and without NEC-associated sepsis (defined as positive blood culture at the time of NEC onset).

RESULTS

A total of 209 infants with medical (n = 98) and surgical NEC (n = 111) had a median gestational age of 27 weeks (IQR 25; 30.5) and a median birth weight of 910 g [IQR 655; 1138]. Fifty of 209 (23.9%) infants had NEC-associated sepsis. Infants with NEC-associated sepsis had lower median GA (26.4 vs. 27.4 weeks; p = 0.01), lower birth weight (745 vs. 930 g; p = 0.009), were more likely mechanically ventilated [p < 0.001], received dopamine [p < 0.001], had more evidence of acute kidney injury [60% vs. 38.4%, p = 0.01], longer postoperative ileus (16 [13.0; 22.0] vs. 12 [8; 16] days; p = 0.006), higher levels of C-reactive protein, lower platelet counts, longer hospitalization compared to infants without NEC-associated sepsis. On multivariate regression, cholestasis was an independent risk factor for NEC-associated sepsis (OR 2.94; 95% CI 1.1-8.8, p = 0.038).

CONCLUSION

NEC-associated sepsis was associated with greater hemodynamic support, acute kidney injury, longer postoperative ileus, and hospitalization on bivariate analysis, and cholestasis was associated with higher odds of sepsis on multi regression analysis.

IMPACT

NEC-associated sepsis was present in 24% of infants with NEC. Gram-positive bacteria, Gram-negative bacteria, and Candida were found in 15.3%, 10.5%, and 2.8% of cases, respectively. Infants with NEC-associated sepsis had a greater inflammatory response (CRP levels), received more blood transfusion before NEC onset, frequently needed assisted ventilation ionotropic support, and had acute kidney injury after NEC onset. NEC infants with Gram-negative sepsis had higher portal venous gas, received more platelet transfusions before NEC onset, and had higher CRP levels and lower median lymphocyte counts at 24 h after NEC onset than those with Gram-positive sepsis.

Transient receptor potential melastatin 7 aggravates necrotizing enterocolitis by promoting an inflammatory response in children

BACKGROUND

As a rare disease in children, necrotizing enterocolitis (NEC) leads to high morbidity and mortality. However, its pathophysiology is largely unclear. Transient receptor potential melastatin 7 (TRPM7) is a membrane protein, which plays key roles in the inflammatory response. This study sought to examine the promoting effect of TRPM7 on NEC in children and explore the therapeutic effect of a TRPM7 inhibitor NS8593.

METHODS

First, we detected TRPM7 and NLR family pyrin domain containing 3 (NLRP3) expression and the state of inflammation in children with NEC through quantitative real-time polymerase chain reaction (RT-PCR), Western blot, and enzyme-linked immunosorbent assays. Next, Human intestinal epithelial cell lines were induced to NEC by lipopolysaccharides (LPSs). The level of cytokines and reactive oxygen species (ROS) were tested by RT-PCR and flow cytometry. The TRPM7 mediated calcium flux were determined by fluorescence. In addition, we used the TRPM7 inhibitor NS8593 to treat the in vivo rat model. The mRNA and protein expression were determined by real-time PCR and Elisa analysis, respectively.

RESULTS

TRPM7 and NLRP3 expression was more increased in the samples from children with NEC compared to the control samples. Additionally, the elevated secretion of interleukin-1β, interleukin-6, and tumor necrosis factor alpha was also detected in the serum of children with NEC. These results showed that TRPM7 had a promoting effect on NEC development, possibly via the activation of NLRP3. To test our hypothesis, the TRPM7 inhibitor NS8593 was used to treat the LPS-stimulated IEC-6 cells. We found that the TRPM7 inhibitor NS8593 inhibited LPS-induced cytokine production and exhibited an anti-inflammatory effect by alleviating TRPM7-mediated NLRP3 inflammasome activation. Through in-vivo experiments, we found that TRPM7 was involved in the occurrence of NEC, and its inhibitor NS8593 played a certain therapeutic role in the rat model.

CONCLUSIONS

Our study revealed TRPM7 inhibitors attenuated LPS-induced ROS and reduced the release of pro-inflammatory cytokines. It also exhibited protective effects on the NEC model.

Brain organoids for addressing COVID-19 challenge

COVID-19 is a systemic disease involving multiple organs, and clinically, patients have symptoms of neurological damage to varying degrees. However, we do not have a clear understanding of the relationship between neurological manifestations and viral infection due to the limitations of current in vitro study models. Brain organoids, formed by the differentiation of stem cells under 3D culture conditions, can mimic the structure of tiny cell clusters with neurodevelopmental features in different patients. The paper reviewed the history of brain organoids development, the study of the mechanism of viral infection, the inflammatory response associated with neurological damage, the detection of antiviral drugs, and combined microarray technology to affirm the status of the brain organoid models in the study of COVID-19. In addition, our study continuously improved the model in combination with emerging technologies, to lay a theoretical foundation for clinical application and academic research.

CXCL1/CXCR2 is involved in white matter injury in neonatal rats via the gut–brain axis

Background

This study aimed to investigate whether CXCL1/CXCR2 mediates intestinal injury or white matter injury by delivering inflammatory mediators through the gut–brain regulation axis.

Methods

Neonatal SD rats, regardless of sex, were administered 3% dextran sulfate sodium via intragastric administration at different time points to construct necrotizing enterocolitis (NEC) models. Meanwhile, hypoxia and ischemia were induced in 3 day-old SD rats to construct hypoxic–ischemic brain injury (HIBI) and NEC + HIBI models, without gender discrimination. Hematoxylin–eosin staining was used to observe pathological changes in neonatal rat intestinal and brain tissues. Western blotting detected CXCL1 and CXCR2 expression in NEC, HIBI, and NEC + HIBI rat intestinal and brain tissues.

Results

Compared with normal rats, pathological damage to periventricular white matter was observed in the NEC group. In addition to the increased mortality, the histopathological scores also indicated significant increases in brain and intestinal tissue damage in both HIBI and NEC + HIBI rats. Western blotting results suggested that CXCL1 and CXCR2 expression levels were upregulated to varying degrees in the intestinal and brain tissues of NEC, HIBI, and NEC + HIBI neonatal rats compared to that in the normal group. Compared with the HIBI group, the expression of CXCL1 and CXCR2 continued to increase in NEC + HIBI rats at different time points.

Conclusions

CXCL1/CXCR2 may be involved in white matter injury in neonatal rats by delivering intestinal inflammatory mediators through the gut–brain axis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12868-022-00749-1.

Pathologically impaired periventricular white matter was observed in NEC neonatal rats.

Hypoxic-ischemic brain injury can also lead to intestinal inflammation.

CXCL1 and CXCR2 were significantly upregulated in intestinal and brain tissues in NEC, HIBI, and NEC+HIBI rats compared to the normal group.

Compared with the HIBI group, CXCL1 and CXCR2 expression continued to increase in NEC+HIBI rats.

Comparison and Investigation of Exosomes from Human Amniotic Fluid Stem Cells and Human Breast Milk in Alleviating Neonatal Necrotizing Enterocolitis

In view of the devastating impact of neonatal necrotizing enterocolitis (NEC) on newborns, the research on its intervention is particularly important. Although exosomes from human amniotic fluid stem cells (AFSC) and human breast milk (HBM) can protect against NEC, their mechanisms remain unclear. Here, we intend to compare the intervention effects of two types of exosomes on NEC mouse model and reveal their respective regulatory mechanisms. In general, both AFSC-derived exosomes (AFSC-exos) and HBM-derived exosomes (HBM- exos) can alleviate NEC- associated intestinal injury, significantly reduce NEC score, and reduce systemic and ileal inflammation and NEC related brain injury during experimental NEC. However, the mode and mechanism of action of the two sources of exosomes were not identical. In vivo, the number of ileal crypts was more significantly restored after HBM-exos intervention than AFSC-exos, and in vitro, HBM-exos preferentially inhibited the inflammatory response of intestinal epithelial cells (IECs), whereas AFSC-exos preferentially regulated the migration of IECs. Mechanistically, GO and KEGG analyses revealed the different therapeutic mechanisms of AFSC-exos and HBM-exos in NEC. Taken together, our results illustrate that AFSC-exos and HBM-exos reduce the severity of experimental NEC and intestinal damage through different mechanisms, supporting the potential of cell-free or breast milk free exosome therapy for NEC.

Graphical Abstract

Vascular dementia: A microglia's perspective

Vascular dementia (VaD) is a second most common form of age-related dementia. It is characterized by cognitive impairment associated with vascular pathology, symptoms mainly caused by cerebral damage due to inadequate blood flow to the brain. The pathogenesis of VaD is complex, and a growing body of literature emphasizes on the involvement of microglia in disease development and progression. Here, we review the current knowledge on the role of microglia in regulating neuroinflammation under the pathogenesis of VaD. The commonly used animal and cell models for understanding the disease pathogenesis were summarized. The mechanisms by which microglia contribute to VaD are multifactorial, and we specifically focus on some of the predominant functions of microglia, including chemotaxis, secretory property, phagocytosis, and its crosstalk with other neurovascular unit cells. Finally, potential therapeutic strategies targeting microglia-modulated neuroinflammation are discussed.

The administration of a pre-digested fat-enriched formula prevents necrotising enterocolitis-induced lung injury in mice

Necrotising enterocolitis (NEC) is a devastating gastrointestinal disease of prematurity that typically develops after the administration of infant formula, suggesting a link between nutritional components and disease development. One of the most significant complications that develops in patients with NEC is severe lung injury. We have previously shown that the administration of a nutritional formula that is enriched in pre-digested Triacylglyceride that do not require lipase action can significantly reduce the severity of NEC in a mouse model. We now hypothesise that this 'pre-digested fat (PDF) system' may reduce NEC-associated lung injury. In support of this hypothesis, we now show that rearing newborn mice on a nutritional formula based on the 'PDF system' promotes lung development, as evidenced by increased tight junctions and surfactant protein expression. Mice that were administered this 'PDF system' were significantly less vulnerable to the development of NEC-induced lung inflammation, and the administration of the 'PDF system' conferred lung protection. In seeking to define the mechanisms involved, the administration of the 'PDF system' significantly enhanced lung maturation and reduced the production of reactive oxygen species (ROS). These findings suggest that the PDF system protects the development of NEC-induced lung injury through effects on lung maturation and reduced ROS in the lung and also increases lung maturation in non-NEC mice.

The administration of amnion-derived multipotent cell secretome ST266 protects against necrotizing enterocolitis in mice and piglets

Necrotizing enterocolitis (NEC) is the leading cause of death from gastrointestinal disease in premature infants and is steadily rising in frequency. Patients who develop NEC have a very high mortality, illustrating the importance of developing novel prevention or treatment approaches. We and others have shown that NEC arises in part from exaggerated signaling via the bacterial receptor, Toll-like receptor 4 (TLR4) on the intestinal epithelium, leading to widespread intestinal inflammation and intestinal ischemia. Strategies that limit the extent of TLR4 signaling, including the administration of amniotic fluid, can reduce NEC development in mouse and piglet models. We now seek to test the hypothesis that a secretome derived from amnion-derived cells can prevent or treat NEC in preclinical models of this disease via a process involving TLR4 inhibition. In support of this hypothesis, we show that the administration of this secretome, named ST266, to mice or piglets can prevent and treat experimental NEC. The protective effects of ST266 occurred in the presence of marked TLR4 inhibition in the intestinal epithelium of cultured epithelial cells, intestinal organoids, and human intestinal samples ex vivo, independent of epidermal growth factor. Strikingly, RNA-seq analysis of the intestinal epithelium in mice reveals that the ST266 upregulates critical genes associated with gut remodeling, intestinal immunity, gut differentiation. and energy metabolism. These findings show that the amnion-derived secretome ST266 can prevent and treat NEC, suggesting the possibility of novel therapeutic approaches for patients with this devastating disease.NEW & NOTEWORTHY This work provides hope for children who develop NEC, a devastating disease of premature infants that is often fatal, by revealing that the secreted product of amniotic progenitor cells (called ST266) can prevent or treat NEC in mice, piglet, and "NEC-in-a-dish" models of this disease. Mechanistically, ST266 prevented bacterial signaling, and a detailed transcriptomic analysis revealed effects on gut differentiation, immunity, and metabolism. Thus, an amniotic secretome may offer novel approaches for NEC.

Initial surgical treatment of necrotizing enterocolitis: a meta-analysis of peritoneal drainage versus laparotomy

Necrotizing enterocolitis (NEC) in premature infants is associated with high morbidity and mortality, and the optimal intervention remains uncertain. To compare the mortality of primary peritoneal drainage versus primary peritoneal laparotomy as initial surgical intervention for NEC. All data were extracted from PubMed, Embase, and the Cochrane Library. Studies published up to December 2021. Patients with NEC. Studies centered on primary peritoneal drainage and primary peritoneal laparotomy as the initial surgical treatment. Mortality outcomes were available for both interventions. Randomized controlled trials, retrospective cohort studies, and case series in peer-reviewed journals. Language limited to English. Odds ratio (OR) with 95% confidence intervals (CIs) was used to evaluate mortality outcome. Subgroup analyses and linear regression were performed to ascertain the association between mortality pre-specified factors. Data of 1062 patients received peritoneal drainage and 2185 patients received peritoneal laparotomy from five case series, five retrospective cohort studies, and three randomized controlled trials. Peritoneal drainage caused similar mortality (OR 1.49, 95% CI 0.99-2.26) compared with peritoneal laparotomy as initial surgical management for NEC infants. The subgroup analysis of study design, sample size, birth weight, and sex showed similar findings, but inconsistent results were found for country (USA: 1.47, 95% CI 0.90-2.41; Canada: 2.53, 95% CI 0.30-21.48; Australia: 10.29, 95% CI 1.03-102.75; Turkey: 0.09, 95% CI 0.01-0.63) and gestational age (age mean difference < 3: 1.23, 95% CI 0.72-2.11; age mean difference ≥ 3: 2.29, 95% CI 1.04-5.05). No statistically significance was found for the linear regression between mortality and sample size (P = 0.842), gestational age (P = 0.287), birth weight (P = 0.257), sex (P = 0.6). Small sample size, high heterogeneity, NEC, and spontaneous intestinal perforation (SIP) had to be analyzed together, lack of selection criteria for the future selection of an intervention, and no clear, standardized procedures.   Conclusion: There was no significant difference in mortality between peritoneal drainage and laparotomy as initial surgical intervention. The results suggest that either intervention could be used in selected patients. What is Known: • Necrotizing enterocolitis (NEC) in premature infants is associated with high morbidity and mortality, and the optimal intervention remains uncertain. What is New: • No significant difference of mortality between peritoneal drainage and laparotomy as initial surgical intervention.

Bench to bedside - new insights into the pathogenesis of necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is the leading cause of death and disability from gastrointestinal disease in premature infants. Recent discoveries have shed light on a unifying theorem to explain the pathogenesis of NEC, suggesting that specific treatments might finally be forthcoming. A variety of experiments have highlighted how the interaction between bacterial signalling receptors on the premature intestine and an abnormal gut microbiota incites a pro-inflammatory response in the intestinal mucosa and its underlying endothelium that leads to NEC. Central amongst the bacterial signalling receptors implicated in NEC development is the lipopolysaccharide receptor Toll-like receptor 4 (TLR4), which is expressed at higher levels in the premature gut than in the full-term gut. The high prenatal intestinal expression of TLR4 reflects the role of TLR4 in the regulation of normal gut development, and supports additional studies indicating that NEC develops in response to signalling events that occur in utero. This Review provides new evidence explaining the pathogenesis of NEC, explores new findings indicating that NEC development has origins before birth, and discusses future questions and opportunities for discovery in this field.

Neurologic consequences of neonatal necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is a severe gastrointestinal disease of the premature infant with high mortality and morbidity. Children who survive NEC have been shown to demonstrate neurodevelopmental delay, with significantly worse outcomes than from prematurity alone. The pathways leading to NEC-associated neurological impairments remain unclear, limiting the development of preventative and protective strategies. This review aims to summarize the existing clinical and experimental studies related to NEC-associated brain injury. We describe the current epidemiology of NEC, reported long-term neurodevelopmental outcomes among survivors, and proposed pathogenesis of brain injury in NEC. Highlighted are the potential connections between hypoxia-ischemia, nutrition, infection, gut inflammation, and the developing brain in NEC.

Novel Therapeutic Targeting of CCL3-CCR4 Axis Mediated Apoptotic Intesitnal Injury in Necrotizing Enterocolitis

Background

Necrotizing enterocolitis (NEC) is the leading cause of neonatal gastrointestinal-related death, while the etiology and pathogenesis are poorly understood.

Methods

The levels of CCL3 in intestinal tissue from modeling mice and patients were measured and analyzed. HE staining, TUNEL, Annexin and FCM were used to assess pathological changes and apoptosis in intestinal tissue and epithelial cells. CCL3, CCR4, cytokines, tight junction protein ZO-1, apoptosis-related genes and ERK1/2-NF-κB signaling pathway were detected by ELISA, Q-PCR, Western blotting and immunofluorescence.

Results

CCL3 levels in the intestinal tissue significantly elevated in patients with NEC and mouse models. Blockade of CCL3 significantly alleviated NEC-related intestinal tissue damage, while administration of recombinant CCL3 aggravated intestinal injury by exacerbating intestinal epithelial cell apoptosis in NEC mice. Importantly, CCR4 blockade reversed CCL3-mediated damage to intestinal tissue and intestinal epithelial cell apoptosis both in vivo and in vitro. Further mechanistic studies showed that CCL3 regulated apoptosis-related BAX/BCL-2 expression through the activation of the ERK1/2 and NF-κB pathways, which could be reversed by anti-CCR4 treatment. Furthermore, ERK1/2 inhibition reduced CCL3-mediated phosphorylation of NF-κB in IEC-6 cells, while inhibition of NF-κB had no obvious effect on ERK1/2 phosphorylation. As expected, inhibition of NF-κB regulated BAX/BCL-2 expression and alleviated CCL3-induced epithelial cell apoptosis. These results indicate that high expression of CCL3 in NEC lesions promotes intestinal epithelial apoptosis through the CCL3-CCR4-ERK1/2-NFκB-BAX/BCL2 signalling axis, thereby exacerbating NEC-related intestinal injury.

Conclusions

Our study represents an important conceptual advance that CCL3 may be one of the key culprits of intestinal tissue damage in NEC patients, and blocking either CCL3, CCR4, or NF-κB may represent a novel effective immunotherapy for NEC.

Human organotypic brain model as a tool to study chemical-induced dopaminergic neuronal toxicity

Oxidative stress is caused by an imbalance between the generation and detoxification of reactive oxygen and nitrogen species (ROS/RNS). This imbalance plays an important role in brain aging and age-related neurodegenerative diseases. In the context of Parkinson’s disease (PD), the sensitivity of dopaminergic neurons in the substantia nigra pars compacta to oxidative stress is considered a key factor of PD pathogenesis. Here we study the effect of different oxidative stress-inducing compounds (6-OHDA, MPTP or MPP⁺) on the population of dopaminergic neurons in an iPSC-derived human brain 3D model (aka BrainSpheres). Treatment with 6-OHDA, MPTP or MPP⁺ at 4 weeks of differentiation disrupted the dopaminergic neuronal phenotype in BrainSpheres at (50, 5000, 1000 μM respectively). 6-OHDA increased ROS production and decreased mitochondrial function most efficiently. It further induced the greatest changes in gene expression and metabolites related to oxidative stress and mitochondrial dysfunction. Co-culturing BrainSpheres with an endothelial barrier using a transwell system allowed the assessment of differential penetration capacities of the tested compounds and the damage they caused in the dopaminergic neurons within the BrainSpheres In conclusion, treatment with compounds known to induce PD-like phenotypes in vivo caused molecular deficits and loss of dopaminergic neurons in the BrainSphere model. This approach therefore recapitulates common animal models of neurodegenerative processes in PD at similarly high doses. The relevance as tool for drug discovery is discussed.

Brain injury in preterm infants with surgical necrotizing enterocolitis: clinical and bowel pathological correlates

BACKGROUND

The objective of this study was to determine the risk factors and outcomes of white matter brain injury (WMBI) on magnetic resonance imaging (MRI) at term-equivalent age in infants with surgical necrotizing enterocolitis (NEC).

METHODS

This retrospective study compared clinical/pathological information between infants with and those without WMBI.

RESULTS

Out of 69 infants with surgical NEC, 17 (24.6%) had mild WMBI, 13 (18.8%) had moderate WMBI, and six (8.7%) had severe WMBI on the brain MRI. Several clinical factors (gestational age, more red blood cell (RBC) transfusions before NEC onset, pneumoperitoneum, earlier NEC onset age, postoperative ileus, acute kidney injury (AKI) by serum creatinine, postnatal steroids, hospital stay) and histopathological findings (necrosis, hemorrhage) had univariate associations with WMBI. Associations with RBC transfusion (odds ratio (OR) 23.6 [95% confidence interval (CI): 4.73-117.97]; p = 0.0001), age at NEC onset (OR 0.30 [95%CI: 0.11-0.84]; p = 0.021), necrosis (OR 0.10 [95%CI: 0.01-0.90]; p = 0.040), and bowel hemorrhage (OR 7.79 [95%CI: 2.19-27.72]; p = 0.002) persisted in multivariable association with grade 3-4 WMBI. The infants with WMBI had lower mean motor, cognitive, language scores, and higher ophthalmic morbidity at 2 years of age.

CONCLUSIONS

The WMBI was most likely associated with earlier NEC onset, higher RBC transfusions, and less necrosis and greater hemorrhage lesions on intestinal pathology in preterm infants with surgical NEC.

IMPACT

In preterm infants with surgical NEC, brain MRI showed injury in the white matter in 52%, gray matter in 10%, and cerebellar region in 30%. Preterm infants with severe WMBI (grade 3-4) had less necrosis and greater hemorrhagic lesions on histopathology of the bowel. Preterm infants with WMBI were more likely to have a more severe postoperative course, AKI, and longer length of hospitalization. Neuroprotective strategies to prevent brain injury in preterm infants with surgical NEC are needed with the goal of improving the neurodevelopmental outcomes.

Early preterm infant microbiome impacts adult learning

Interventions to mitigate long-term neurodevelopmental deficits such as memory and learning impairment in preterm infants are warranted. Manipulation of the gut microbiome affects host behaviors. In this study we determined whether early maturation of the infant microbiome is associated with neurodevelopment outcomes. Germ free mice colonized at birth with human preterm infant microbiomes from infants of advancing post menstrual age (PMA) demonstrated an increase in bacterial diversity and a shift in dominance of taxa mimicking the human preterm microbiome development pattern. These characteristics along with changes in a number of metabolites as the microbiome matured influenced associative learning and memory but not locomotor ability, anxiety-like behaviors, or social interaction in adult mice. As a regulator of learning and memory, brain glial cell-derived neurotrophic factor increased with advancing PMA and was also associated with better performance in associative learning and memory in adult mice. We conclude that maturation of the microbiome in early life of preterm infants primes adult associative memory and learning ability. Our findings suggest a critical window of early intervention to affect maturation of the preterm infant microbiome and ultimately improve neurodevelopmental outcomes.

The Future of 3D Brain Cultures in Developmental Neurotoxicity Testing

Human brain is undoubtedly the most complex organ in the body. Thus, it is difficult to develop adequate and at the same time human relevant test systems and models to cover the aspects of brain homeostasis and even more challenging to address brain development. Animal tests for Developmental Neurotoxicity (DNT) have been devised, but because of complex underlying mechanisms of neural development, and interspecies differences, there are many limitations of animal-based approaches. The high costs, high number of animals used per test and technical difficulties of these tests are prohibitive for routine DNT chemical screening. Therefore, many potential DNT chemicals remain unidentified. New approach methodologies (NAMs) are needed to change this. Experts in the field have recommended the use of a battery of human in vitro tests to be used for the initial prioritization of high-risk environmental chemicals for DNT testing. Microphysiological systems (MPS) of the brain mimic the in vivo counterpart in terms of cellular composition, recapitulation of regional architecture and functionality. These systems amendable to use in a DNT test battery with promising features such as (i) complexity, (ii) closer recapitulation of in vivo response and (iii) possibility to multiplex many assays in one test system, which can increase throughput and predictivity for human health. The resent progress in 3D brain MPS research, advantages, limitations and future perspectives are discussed in this review.

Methodologies for Generating Brain Organoids to Model Viral Pathogenesis in the CNS

(1) Background: The human brain is of interest in viral research because it is often the target of viruses. Neurological infections can result in consequences in the CNS, which can result in death or lifelong sequelae. Organoids modeling the CNS are notable because they are derived from stem cells that differentiate into specific brain cells such as neural progenitors, neurons, astrocytes, and glial cells. Numerous protocols have been developed for the generation of CNS organoids, and our goal was to describe the various CNS organoid models available for viral pathogenesis research to serve as a guide to determine which protocol might be appropriate based on research goal, timeframe, and budget. (2) Methods: Articles for this review were found in Pubmed, Scopus and EMBASE. The search terms used were "brain + organoid" and "CNS + organoid" (3) Results: There are two main methods for organoid generation, and the length of time for organoid generation varied from 28 days to over 2 months. The costs for generating a population of organoids ranged from USD 1000 to 5000. (4) Conclusions: There are numerous methods for generating organoids representing multiple regions of the brain, with several types of modifications for fine-tuning the model to a researcher's specifications. Organoid models of the CNS can serve as a platform for characterization and mechanistic studies that can reduce or eliminate the use of animals, especially for viruses that only cause disease in the human CNS.